The elimination of contaminants from gaseous emissions by exposure to plasma under controlled conditions, is generally known in the art as disclosed for example in U.S. Pat. No. 5,137,701 to Mundt and in applicant""s prior U.S. Pat. No. 5,468,356. The plasma according to such prior art disclosures is generated by use of microwave radiation. It is also generally known that such plasma may be generated by a corona discharge process that is relatively costly, involving impact ionization of neutrals by electrons accelerated by a high level electric field within a gaseous medium. It is therefore an important object of the present invention to provide a less costly method of eliminating contaminants from gaseous emissions by exposure to a plasma during its generation by a corona discharge process.
Pursuant to the present invention, a corona discharge system is utilized to generate plasma for elimination of contaminants such as air polluting oxides within emission gas discharged from hot chamber incinerators. Use of the corona discharge system is rendered economically suitable because of reduced and less costly power consumption associated with the generation of plasma to which the contaminants are exposed. Such corona discharge system involves the supply of electrical pulse energy, in excess of a critical voltage level, for breakdown of an electric field initially established within a reactor chamber through which the gaseous emission is conducted under atmospheric pressure and a high temperature. Plasma generation in response to such electric field breakdown within the hot reaction chamber is thereby effected more efficiently than in a cold chamber in view of a drastic decrease in the required electrical energy consumption for corona discharge with increase in temperature.